Pet allergies.

Do you sneeze at your Siamese? If so, you're one of the millions who have pet allergies. "Allergies to pets are not present when a child is first born," says Dr. Rebecca Gruchalla, an allergy expert and instructor of internal medicine at UT Southwestern Medical Center at Dallas. "Pet allergies take months or years to develop. And even if the pet is banished from the house or given away, the antigen persists for months. Eventually, after intense cleaning, it's removed."

When you sneeze at your cat, you're really sneezing at Fel d1, a protein present in a cat's skin, as well as in its saliva glands. As the cat licks its fur, it deposits these proteins on its body. When the moist Fel d1 particles dry, they are dispersed into the air and find their way into a person's nostrils.

Washing the cat reduces the amount of the antigen on its fur. Of course cats don't like baths much, but they'll eventually get used to it, especially if you start the weekly baths when the cat is a kitten. Check with your veterinarian about the type of soap to use, if any, and use only warm water. Rather than dunking your cat, wet the animal slowly and wear gloves to avoid being scratched. Studies show that washing a cat once a week reduces the level of allergen coming off the cat 90 percent.

While dog allergies are not as prevalent as cat allergies, they do exist. Gruchalla says a person may be allergic only to certain breeds of dogs. Unfortunately, she adds, while dog-specific antigens have been identified in dog dander, there is still no evidence that washing the dog will reduce the symptoms.

If you suspect you have a pet allergy, see a board-certified allergist for an evaluation. What you think is a pet allergy may be an allergy to dust or mold.